The AFD e85 injector question: Stock or Upgraded?

[ChapterM3]

Hey Everyone,

So I'm freakin out over here. I'm reading the thread "is my s54 hydrolocked" and I'm thinking to myself: "My f-ing god, I have 140k miles on my stock injectors, I've been running the AFD (Advanced fuel dynamics) kit on my car for over a year, am I leaning out my engine unknowingly?! F-ing hell I need to get this figured out." I've read all kinds of opinions: "bro stock injectors are 100% maxed out with e85, your motor is leaning out" to "the AFD kit is suited for stock injectors, you're fine" - Let's put this question to bed, shall we?

My Setup -
- S54 engine (M3) @ 141k
- Stock injectors / fuel system with 141k
- Shark tune
- Intake / section 1,2,3 done / VANOS rebuit, etc / I don't know what else you would want to know for engine mods but that's what I got in my head that matters

How often do I run e85?
- When I got the car last year in 2019, almost every tank for like 4 months
- Now: Once in a blue moon, most recently last month, the car was a rocketship, then went back to 93

Why do I run e85?
- I love the environmental reason behind it. Keeping a 16 year old car running and on corn, which is on a closed co2 cycle is awesome (Corn grows-> dies -> made into fuel -> burned -> atmosphere -> corn plants absorb it). I'm happy to do a tiny micro part for the environment to continue to use a piece of engineering instead of buying a new one with all that goes into manufacturing a car and be able to drive/have fun.
- The car is a f-ing animal with it. Usually, I get around e70-78 at my local pump and it's a massive difference in power that I can feel. It's a blast.

My Concerns -
- I have 141k on my stock injectors - I want to buy new ones this winter to make sure I stay ahead of maintenance from the dreaded EML light and also because sometimes the car does have a rough idle at startup and I've been reading that is the culprit most of the time. I've run fuel injector cleaner in there and the car improved its MPG significantly and now settled back into the 22mpg region

The main questions for you -
- Do I buy upgraded injectors or just buy stock again? And the reason behind that choice?
- If it is upgraded injectors: what size and why? I will not be boosting the car at all in the future.
- If I buy bigger injectors, can I still run 93 and e85 or will the car run like junk on 93?

Let's put this question to bed as I know I'm not the only one wondering on this!

Thank you!!!

Jonathan

[dl.m3]

Stock injectors definitely cannot handle full E85. I'd advise larger injectors and then re tune. I would also highly recommend a wideband O2 sensor to see AFRs.

As for leaning out, you might've gotten lucky that the cooling effect of E85 kept your pistons from melting due to running lean.

Sent from my HD1905 using Tapatalk

[EthanolTurbo]

Get upgraded injectors. You will need to get a custom flash tune but they'll work fine with E85 or 93. That extra overhead is worth it.

[ChapterM3]

Hey guys - Just wanted to report back on some investigation I did. Thank you both for the comments!

I took your comments to heart and say F man I have to call someone that deals with this stuff professionally. So I emailed one of the most well spoken of tuners in the Boston area (also a friend of mine from HS) and explained my situation and with the AFD kit. They told me that e85 does not max out our injectors on the proper tune. If I get tuned, there's no issue running the stock ones, given that they're at their normal flow capacity. So with that being said, for me, I believe that I'll have a new tune put on the car and get a new set of stock injectors.

Of course, I'm still open for discussion so please if you still have input here let me know - I welcome the conversation!

[Triqzy]

Hello it's Mr. Hydrolock over here haha. Personally swapping the injectors was very easy all things considered, especially since it's right on top of the motor and no special tools required. I think the answer to your question depends on how much money you want to spend here. Swapping in new OEM injectors are plug and play, new from FCPeuro I only spent around $240. It was $125 if i wanted them professionally cleaned, but I didn't want to wait on down time and for the extra $100 I can replace them whenever.

That being said, if you have the money to spend on injectors + a tune I don't see why not upgrade if you're already replacing old OEM injectors. Personally with my own financial situation, I just would rather put that money somewhere else when prioritizing mods/maintenance. Also I don't think your friend is correct. Everything I've read on this forum, E85 cannot be run on the stock injectors because the duty cycle is too high at that % and 8k rpm..

[Obioban]

Piggyback everything is a recipe for issues, sooner or later.